An image-forming device such as a laser printer for forming color images on recording sheets is well known in the art. One such image-forming device has a plurality of photosensitive members and a plurality of corresponding developer cartridges (each integrally formed of a developing device and a developer-accommodating device) arranged in tandem and held at fixed positions within a retaining member. Parts, consumables, and the like in the photosensitive members and the developer cartridges can be replaced by pulling the retaining member out from a body of the image-forming device along the direction in which the photosensitive members are juxtaposed.